Pope Francis offered his full support for UN efforts to end the conflicts in Syria and Libya in his Christmas message on Friday.

"We pray... that the agreement reached in the United Nations may succeed in halting as quickly as possible the clash of arms in Syria and in remedying the extremely grave humanitarian situation of its suffering people," he said.

"It is likewise urgent that the agreement on Libya be supported by all, so as to overcome the grave divisions and violence afflicting the country."

The UN Security Council last week unanimously adopted a resolution endorsing a proposed peace plan to bring the Syrian government of President Bashar al-Assd and opposition together for talks in January.

The plan followed nearly two months of strenuous efforts among top diplomats from 17 countries, including Assad's backers Russia and Iran.

Syria's government said on Thursday it was ready to take part in new talks in Geneva aimed at ending the war, though it appeared to make its participation conditional on which opposition groups attend.

On Wednesday, the UN Security Council gave its backing to the new national unity government in embattled Libya, a move it hopes will help stem mass migration to Europe and reverse gains made by militants from the Islamic State (IS) group.

The 15-nation council gave its support to the deal signed last week in the Moroccan town of Skhirat between representatives of strife-torn Libya's two competing regimes.

Solidarity with migrants

Pope Francis also used his Christmas message to call for solidarity with migrants while praising those who shelter them.

"May God repay all those, both individuals and states, who generously work to provide assistance and welcome to the numerous migrants and refugees," Francis said after a year that saw more than one million migrants reach Europe.

He called for "encouragement ... to all those fleeing extreme poverty or war, travelling all too often in inhumane conditions and not infrequently at the risk of their lives".

Francis praised those who are helping migrants "to build a dignified future for themselves and for their dear ones, and to be integrated in the societies which receive them".

The Pope also denounced the destruction of cultural heritage, in a clear reference to IS militants.

He said "atrocities" committed by IS "do not even spare the historical and cultural patrimony of entire peoples".